The team at Yahoo! Answers is somewhat split on the outcome; responses include "No. The lightsaber is a laser and lasers can not hurt superman" and "dude, lightsabers can cut through anything! even superman," but thankfully our nerd powers are strong on this one - The answer is, probably not, unless he's already been weakened by either magic or kryptonite at the time.

Of course, if the lightsaber in question is powered by a kryptonite crystal, then he's going to be in pieces faster than you could say "Cut off his hand! Cut off his hand!!!"

Can a Jedi lightsaber cut through Superman? [Yahoo! Answers]